Balloon with variable pitch reinforcing fibers

ABSTRACT

A medical balloon includes a generally cylindrical barrel wall having proximal and distal ends disposed between tapered cone walls and neck walls with a fiber layer comprised of circumferentially wrapped ribbon-shaped fiber embedded in a continuous matrix of polymer material defining the tapered cone walls and barrel wall, wherein the distance between the fiber wraps defines a fiber pitch or density that varies over the working length of the barrel wall in non-linear increments, for example in step-wise increments over the length of the barrel wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/245,453, filed on Sep. 24, 2009.

TECHNICAL FIELD

The following disclosure relates to medical dilation balloons; and, inparticular, it relates to non-compliant and semi-compliant medicalballoons useful in angioplasty, stent placement and dilation and othermedical applications including cardiology, radiology, urology andorthopedics.

BACKGROUND

Medical balloons are increasingly used in a wide variety of medicalprocedures. Typically, an uninflated medical balloon is inserted into abody-space, e.g., blood vessel, urological vessel, etc. by means of acatheter. After positioning at the desired location within the body, themedical balloon may be inflated by introducing a pressurized fluid intothe balloon through the catheter. The pressurized fluid causes themedical balloon to expand, and the adjacent body-space is similarlyexpanded. The fluid may then be withdrawn from the balloon, causing itto collapse to facilitate its removal from the body. Medical balloonsare also used for temporarily occluding vessels, placing medical devicessuch as stents, drug delivery and heat transfer.

Medical dilation balloons may be used to perform peripheral, forexample, below-the knee, angioplasty to open a stenosis or occlusion ofan artery, with or without stent placement. In some instances, thisprocedure requires that the balloon be threaded through small bloodvessels along a tortuous path. Placement of the balloon may require thatthe balloon be forced through long calcified occlusions. Consequently, anumber of characteristics are desired for medical dilation balloons usedin these procedures.

In order to traverse a tortuous path to and/or through an occlusion, ahigh degree of trackability is desirable. In this context, the term“trackability” refers to the capability to traverse sharp turns orbranches of the vessels or body cavities through which a balloon mustpass. Balloons having more flexible walls generally provide bettertrackability. Since the balloon may be pushed through narrow and/oroccluded blood vessels, a low profile (i.e., diameter) in the deflatedstate is also desirable. Further, a balloon should have good scratchresistance to avoid damage if it is pushed through a calcifiedocclusion.

Balloons used to place stents (an expandable metal sleeve), should havehigh puncture resistance, particularly at the areas of the balloon atthe end of the stent. To avoid damaging the blood vessel's walls, thedilation balloon should exhibit low compliance. Balloon compliance is aterm used to describe the change in a balloon's diameter as a functionof pressure. Since the balloon may be used to open or expand toughtissues such as strictures, scarred or calcified areas, high pressuresmay be required. Thus, a balloon used in these applications should havehigh operating and burst pressures. The rated burst pressure istypically the maximum pressure at which there is a statistical 95%confidence level that 99.9% of the population of balloons will notburst. High-pressure non-compliant balloons may have rated burstpressures of up to 20 atmospheres or higher.

Generally, high pressure, non-compliant balloons are formed fromrelatively noncompliant (e.g. relatively inelastic) materials such asoriented highly crystalline polyethylene terephthalate (PET) films. SuchPET films provide high tensile strength, and may be used to formballoons with thin walls having high burst pressures. However, balloonsformed from PET and similar materials having a high strength relative towall thickness tend to be susceptible to puncture and scratching.

Non-compliant medical balloons for performing angioplasty and othermedical procedures are known. U.S. Pat. No. 6,746,425 to Beckhamdiscloses a semi-compliant medical balloon and methods for manufacturingthe balloon. U.S. Patent Application Publication No. US 2006/0085022 toHayes et al. discloses a semi-compliant medical balloon having anintegral woven fabric layer and methods for manufacturing the balloon.U.S. Patent Application Publication No. US 2006/0085023 to Davies, Jr.et al. discloses a medical balloon having strengthening rods and methodsfor manufacturing the balloon. U.S. Patent Application Publication No.US 2006/0085024 to Pepper et al. discloses a semi-compliant medicalballoon having an integral non-woven fabric layer and methods formanufacturing the balloon. U.S. Pat. No. 6,746,425 and Publication Nos.US 2006/0085022, US 2006/0085023 and US 2006/0085024 are herebyincorporated herein by reference.

However, a need exists for improved medical dilation balloons having alow degree of compliance, thin walls, puncture resistance and improvedtrackability.

SUMMARY

In one aspect thereof, a fiber-reinforced medical balloon that may beinflated and deflated includes a generally cylindrical barrel wallhaving proximal and distal ends disposed between tapered cone walls andproximal and distal cylindrical neck walls extending from the conesalong a longitudinal axis. The balloon includes a fiber layer embeddedin a continuous matrix of polymer material defining a barrel wall, conewalls and neck walls wherein the barrel wall has a working lengthbetween the tapered cone walls. The fiber of the fiber layer extendscircumferentially around the longitudinal axis of the balloonsubstantially over the entire length of the balloon including the neckwalls, the cone walls and the barrel wall. The fiber pitch varies alongthe working length of the barrel portion with the fiber pitch in a firstportion of the barrel wall being less than the fiber pitch in a secondportion of the barrel wall. The working length of the balloon may varyfrom about four centimeters to about twenty-five centimeters, dependingupon the specific application. In different embodiments, the balloon maybe non-compliant or semi-compliant.

In one embodiment, the fiber pitch decreases from the proximal end ofthe barrel wall to the distal end of the barrel wall continuously or ina step-wise incremental manner. In another variation, the fiber pitch infirst and second longitudinally spaced apart portions of the barrel wallis greater than the fiber pitch in a third portion of the barrel wallseparating the spaced apart portions. In another embodiment, the fiberpitch in first and second longitudinally spaced apart portions of thebarrel wall is less than the fiber pitch in a third portion of thebarrel wall separating the first and second portions. In yet anothervariation, the fiber pitch in first, second and third longitudinallyspaced apart portions of the barrel wall is greater than the fiber pitchin longitudinally spaced apart fourth and fifth portions of the barrelwall separating the first, second and third portions of the barrel wall.

In another embodiment, a medical balloon includes a generallycylindrical barrel wall having proximal and distal ends disposed betweentapered cone walls. The balloon includes a fiber layer comprised ofribbon-shaped fiber embedded in a continuous matrix of polymer materialdefining tapered cone walls and a barrel wall disposed between thetapered cone walls. The fiber of the fiber layer extends around thelongitudinal axis of the balloon in a series of circumferential fiberwraps with the distance between the fiber wraps defining a fiber pitchor density. In one aspect, the distance between adjacent fiber wrapsvaries over the working length of the barrel wall in non-linearincrements, for example in step-wise increments over the length of thebarrel wall.

In one aspect, the fibers of the fiber layer are ribbon-shaped, having awidth-to-thickness ratio in the range from about 25:1 to about 45:1. Inother variations, the fibers may have a width-to-thickness ratio in therange from about 30:1 to about 40:1. The medical balloon may alsoinclude distal cylindrical neck walls, the neck walls extending along alongitudinal axis of the balloon, extending from the cone walls along alongitudinal axis of the balloon with the fiber layer extendingcontinuously between the ends of the neck walls around the cone sectionsand barrel wall. The flattened or ribbon-shaped fibers allow for thinnerballoon walls while simultaneously reinforcing the balloon. The fibersmay be formed from substantially inelastic or semi-elastic materials.

In yet another embodiment, an inflatable fiber-reinforced medicalballoon includes a base balloon or base layer formed from a polymermaterial defining a barrel wall having a working length, cone wallsextending from the barrel wall and neck walls extending from the conewalls along a longitudinal axis of the balloon. A fiber layer isdisposed over the base balloon and extends over the working length ofthe barrel wall in a series of circumferential fiber wraps. The distancebetween adjacent circumferential wraps of the fiber defines a fiberpitch or density. An outer layer is formed from a polymer material isdisposed over the fiber layer and adhered to the base balloon. The fiberpitch varies linearly or non-linearly over the working length of theballoon.

In another aspect, the walls of barrel portion and cone sections of theballoon form pleats or folds with creases between the folds. The foldsor pleats extend longitudinally from proximal neck portions along thelength of the cone and barrel portions of the balloon. In one embodimentat least three folds are formed in the walls of the cone and barrelportions of the balloon. In other variations, a greater or lesser numberof folds and creases may be formed, for example two, four, six or tenfolds may be formed. This pleated construction of the cone and barrelsections reduces the diameter of balloon to facilitate insertion of theballoon in its deflated state. Once positioned at the desired location,the balloon may be inflated through a catheter with a pressurized fluidsuch as a saline solution. As balloon is inflated, the folds and creasesdisappear as the balloon reaches a fully inflated size such that theoutside surface of the balloon assumes a substantially smooth profile.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding, reference is now made to thefollowing description taken in conjunction with the accompanyingDrawings in which:

FIG. 1A is a partially cut away side view of a medical balloon withvariable pitch fiber in an inflated state illustrating reinforcingfibers embedded in a wall of the balloon;

FIG. 1B is a perspective view of the balloon of FIG. 1 in a deflatedstate;

FIG. 1C is a partial longitudinal sectional view through the barrel wallof the balloon of FIG. 1A;

FIG. 2A illustrates the arrangement of reinforcing fibers in a firstembodiment of a medical balloon according to the disclosure;

FIG. 2B is a graph representing the fiber pitch along the working lengthof the medical balloon of FIG. 2A;

FIG. 3A illustrates the arrangement of reinforcing fibers in a secondembodiment of a medical balloon according to the disclosure;

FIG. 3B is a graph representing the fiber pitch along the working lengthof the medical balloon of FIG. 3A;

FIG. 4A illustrates the arrangement of reinforcing fibers in a thirdembodiment of a medical balloon according to the disclosure;

FIG. 4B is a graph representing the fiber pitch along the working lengthof the medical balloon of FIG. 4A;

FIG. 5A illustrates the arrangement of reinforcing fibers in a fourthembodiment of a medical balloon according to the disclosure;

FIG. 5B is a graph representing the fiber pitch along the working lengthof the medical balloon of FIG. 5A;

FIG. 6A illustrates the arrangement of reinforcing fibers in a fifthembodiment of a medical balloon according to the disclosure;

FIG. 6B is a graph representing the fiber pitch along the working lengthof the medical balloon of FIG. 6A;

FIG. 7 illustrates the placement of reinforcing fibers on a baseballoon;

FIG. 8 illustrates the application of an outer cover layer over thefiber wrapped balloon of FIG. 7; and

FIG. 9 illustrates the placement of the balloon of FIG. 8 in a die forheating and finishing of the balloon.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numbers are usedherein to designate like elements throughout, the various views andembodiments of a balloon with variable pitch reinforcing fibers areillustrated and described, and other possible embodiments are described.The Figures are not necessarily drawn to scale, and in some instancesthe drawings have been exaggerated and/or simplified in places forillustrative purposes only. One of ordinary skill in the art willappreciate the many possible applications and variations based on thefollowing examples of possible embodiments.

FIG. 1A is a side view of a fiber-reinforced semi-compliant medicaldilation balloon according to one embodiment. As illustrated, medicalballoon 100 is shown in a fully inflated state. Balloon 100 includes agenerally cylindrical barrel portion 102 disposed between taperedproximal and distal cone portions 104 a, 104 b. A cylindrical proximalneck portion 106 a and a cylindrical distal neck portion 106 b extendfrom cone portions 104 a, 104 b along a longitudinal axis 108 of theballoon. The outer surface 110 of cone portions 104 a, 104 b each forman angle 112 (the “cone angle”) with respect to a longitudinal extensionof the wall of the barrel portion 102. In some embodiments, balloon 100may have a cone angle 112 in the range of 12 degrees to 22 degrees, inothers from 18 degrees to 22 degrees. Higher cone angles provide ashorter total balloon length and in some embodiments, the cone angle 112is about 20 degrees. Balloon 100 may have a working length L1 betweencone sections 104 a, 104 b of 4 to 25 cm or longer. In one embodiment,barrel portion 102 of balloon 100 comprises a generally cylindrical wall124 with one continuous or a plurality of circumferential fibers 126embedded in the wall.

In one embodiment, balloon 100 is non-compliant, i.e., it will expandtypically less than about 5%, when pressurized from a nominal operatingpressure to a rated burst pressure. In another embodiment, balloon 100is semi-compliant, i.e. it will expand radially from about 5% to about20% from its fully inflated diameter at a nominal operating pressure asthe pressure of the fluid used to inflate the balloon increases to theballoon's rated burst pressure. While balloon 100 may be constructed toany dimensions, balloons having a deflated diameter in the range fromabout 2 French Units to about 12 French Units are useful in the fieldsof cardiology, radiology, orthopedics and urology. In one embodiment,balloon 100 has a deflated diameter in the range of 2 to 12 French Unitsand a folding wall thickness of less than about 0.002 inches.

Referring to FIG. 1B, balloon 100 is illustrated in a deflated state. Inits deflated state, the walls of barrel portion 102 and cone sections104 a, 104 b of balloon 100 form pleats or folds 120 with creases 122between the folds. As illustrated folds 120 extend longitudinally fromproximal neck portion 106 a to the opposing distal neck portion 106 b.In one embodiment, at least three pleats or folds are formed, while inother embodiments, a greater or less number of folds or pleats may beformed to reduce the diameter of balloon 100 in its deflated state. Thepleated construction of the cone and barrel sections, 104 a, 104 b and102 reduces the diameter of balloon 100 to facilitate insertion of theballoon in its deflated state. Once positioned at the desired location,balloon 100 may be inflated through a catheter with a pressurized fluidsuch as a saline solution. As balloon 100 is inflated, folds and creases120, 122 substantially disappear as the balloon reaches a fully inflatedsize.

FIG. 1C is a partial longitudinal section of barrel section 102 ofballoon 100 according to one embodiment. As illustrated, barrel wall 124includes one or more circumferential reinforcing fibers 126 embedded ina polymer layer 128 to form a fiber-reinforced wall structure. In oneembodiment, a single fiber 126 extends from the proximal to the distalend of balloon 100 in a series of circumferential loops or wraps aroundthe diameter of the balloon. As illustrated, fibers 126 aresubstantially ribbon-shaped in order to maintain the cross-sectionalarea and strength of the fiber while providing for a thinner wall 124.In different embodiments, fibers 126 may have a width-to-thickness ratioin the range from about 25:1 to about 45:1; in other variations, thefibers may have a width-to-thickness ratio in the range from about 30:1to about 40:1.

Fibers 126 may be originally supplied in the form of a bundle or “tow”of individual filaments. The tow typically has a generally circularcross-section and may include an adhesive to hold the filaments togetherand retain the cross-sectional shape of the tow. Before use inconstructing balloon 100, the tow is drawn between one or more pair ofclosely spaced rolls to flatten the tow. A solvent or solvent-basedadhesive may be applied to the tow before it is drawn between the rollto soften any previously applied adhesive and to facilitaterearrangement of the filaments within the tow. After flattening, thefiber may be dried, if necessary, and used or stored for later use.

For non-compliant balloons, substantially inelastic reinforcing fibers126 may be used. The reinforcing fibers 126 may be made from a varietyof inelastic materials, including, but not limited to, Kevlar, Vectran,Spectra, Dacron, Dyneema, Turlon (PBT), Zylon (PBO), polyimide (PIM) andother ultrahigh molecular weight polyethylenes, aramids, and the like.In one embodiment, reinforcing fibers 126 may be multi-filament aramidor para-aramid fibers. In one variation, the fibers may be Technora®brand paraphenylene/3,4-oxydiphenylene/terephthalamide copolymer,preferably multi-filament. For semi-compliant balloons, reinforcingfibers 126 may be semi-elastic and have an elongation to break of fromabout 10% to about 20%. Reinforcing fibers 126 for a semi-compliantballoon may be formed from a nylon, such as nylon 6 or 6.6 or a hightenacity polyester.

Referring still to FIG. 1C, polymer base layer 128 may be formed frompolymers and copolymers used in medical balloon construction, such as,but not limited to, polyethylene, polyethylene terephthalate (PET),polycaprolactam, polyesters, polyethers, polyamides, polyurethanes,polyimides, ABS copolymers, polyester/polyether block copolymers andionomer resins. In one variation, barrel wall 124 may include an outercoating or layer 130, which may be the same as or similar to the polymermaterial in layer 128. In one variation, layers 128 and 130 may beformed from thermally-weldable materials such that the layers may bebonded or adhered together by heating. In other variations, a suitableadhesive such as a polyurethane may be used to bond layers 128 and 130.In still other embodiments, layers 128 and 130 may be bonded by solventwelding, ultrasonic, laser or infrared welding or other known methods.

The materials that form layer 128 and fibers 126 and outer layer 130should be physically compatible. For example, if layer 128 is too soft,(e.g. too elastic, low tensile strength) relative to the material offibers 126, the base balloon may extrude and/or blow out between fibers126 at less than the desired operating pressure. Alternatively, if thematerial of layer 128 is too hard (e.g. too inelastic, high tensilestrength) relative to fibers 126, balloon 100 may fail prematurely.Thus, the tensile properties (elasticity, tensile strength andelongation to break) of the materials used to form layer 128 and fibers126 should be matched to prevent failure of the balloon while providingthe desired burst pressure and level of compliance. For semi-compliantballoons, outer layer 130 should have suitable tensile properties(elasticity, tensile strength and elongation to break) sufficient topermit moderate expansion (5% to 20%) in a radial direction.

Referring still to FIG. 1C, the distance or “pitch” 132 betweencircumferential fibers 126 may vary over the length of the balloon 100.As used herein, the term “pitch” refers to the distance between fibers126 measured from the center of one fiber to the center of an adjacentfiber along the longitudinal axis 108 of balloon 100. Thus, the “pitch”of fibers 126 may be expressed as the number of fibers per unit length,for example the number of fibers per inch. In one embodiment, balloon100 includes a single fiber layer comprising variable pitchcircumferential fiber or fibers 126. In other embodiments, balloon 100may include additional fiber layers including longitudinally extendingfibers, woven or non-woven fibers or knitted fibers. Balloon 100 mayalso include additional polymer layers.

FIG. 2A is a side view of one embodiment of a medical balloon 200illustrating the arrangement of one or more circumferential reinforcingfiber(s) 230 having an incrementally stepped variable fiber pitch alongthe length of the balloon. Balloon 200 has a generally cylindricalbarrel portion 202 having a working length L2, a proximal end 204 and adistal end 206. Barrel portion 202 is disposed between a proximal coneportion 208 and a distal cone portion 210. Proximal and distal neckportions 212, 214 extend longitudinally from proximal and distal coneportions 208 and 210. In one embodiment, the working length L2 of barrelportion 202 may be divided in a plurality of longitudinally extendingzones 216, 218, 220, 222, 224 and 226, each of which has a differentfiber pitch. In one embodiment, a single fiber 230 extendscircumferentially around the diameter of balloon 200 from the proximalend 232 to the distal end 234 of balloon 200. In other embodiments, aplurality of fibers 230 may be used to reinforce balloon 200.

FIG. 2B is a graph illustrating the fiber pitch in each of zones216-226. As shown, the fiber pitch in zones 216-226 decreases in astep-wise fashion along the working length L2 of balloon 200 from theproximal end 204 of barrel portion 202 to the distal end 206 of thebarrel portion. For example, the fiber pitch in zones 216-226 may bevaried as followed:

Zone: 216 218 220 222 224 226 Fiber Pitch: 56 48 38 30 25 20

It will be appreciated that this example of the changes in the fiberpitch along barrel portion 202 of balloon 200 is only to illustrate onepossible arrangement. The actual change in fiber pitch may vary due to awide variety of factors including the size of balloon 200, the materialsused to fabricate the balloon, the size of fibers 230, the material fromwhich the fibers are made and the desired characteristics of theballoon. A greater or lesser number of zones having different fiberpitches may also be employed to achieve the desired characteristics.

In one embodiment, the fiber pitch in each of zones 216-226 remains thesame within each zone, changing at the junctions between adjacent zones.Although as illustrated, the fiber pitch decreases in a step-wisefashion, other variations are possible. For example, there may betransition areas between zones 216-226 where the fiber pitch changesover segments of the working length L2 of barrel portion 202 in a linearor non-linear fashion.

Referring still to FIGS. 2A and 2B, decreasing the fiber pitch from theproximal end 204 of barrel portion 202 to the distal end 206 of thebarrel portion reduces the stiffness of balloon 200 along the workinglength of the balloon. This, in turn, increases the trackability of thedistal portion of balloon 200, increasing the balloon's capability totraverse sharp turns or branches of the blood vessels. Reducing thestiffness of the distal portion of balloon 200 may also decrease therisk of damaging a vessel wall. Alternatively, the more heavilyreinforced proximal portion of balloon 200, wherein the closely spacedfibers 230 provide greater strength and puncture resistance, may be usedto force open stenotic lesions.

In the illustrated embodiment, the fiber pitch in the proximal cone andneck portions 208, 212 of balloon 200 is substantially the same as thefiber pitch in the adjacent zones 216, 226 of barrel portion 202.Similarly, the fiber pitch in distal cone and neck portions 210, 214 ofballoon 200 is the same or substantially the same as in the adjacentzones 216, 226 of barrel portion 202. In other embodiments, the fiberpitch in the cone portions 208, 210, and neck portions 212, 214 may bevaried to improve the trackability or other characteristics of balloon200.

FIG. 3A is a side view of an embodiment of a medical balloon 300 havinga continuously variable fiber pitch. Balloon 300 has a generallycylindrical barrel portion 302 having a working length L3, a proximalend 304 and a distal end 306. Barrel portion 302 is disposed between aproximal cone portion 308 and a distal cone portion 310. Proximal anddistal neck portions 312, 314 extend longitudinally from proximal anddistal cone portions 308 and 310. In the illustrated embodiment, one ormore fibers 330 extend circumferentially around the diameter of balloon300 from the proximal end 332 to the distal end 334 of balloon 300.

FIG. 3B is a graph illustrating the change in fiber pitch over theworking length of balloon 300. As illustrated, the fiber pitch decreaseslinearly from the proximal end 304 of barrel portion 302 to the distalend 306 of the barrel portion. For example, the fiber pitch may decreaselinearly from about 60 fibers per inch at the proximal end 304 of barrelportion 302 to about 20 fibers per inch at the distal end 306 of thebarrel portion. In other variations, the fiber pitch may decreasecontinuously in a non-linear manner from the proximal end 304 of barrelportion 302 to the distal end 306 of the barrel portion. For example,the fiber pitch may decrease along the curve represented by the dashedline in FIG. 3B. Decreasing the fiber pitch from the proximal end 304 ofbarrel portion 302 to the distal end 306 of the barrel portion reducesthe stiffness of balloon 300 along the working length of the balloon,increasing the trackability of the distal portion of the balloon.

Stents are small, collapsible sleeves, typically formed from stainlesssteel and/or a suitable plastic that may be used in conjunction withangioplasty. For example, if a blood vessel does not remain open afterangioplasty, a stent can be placed and expanded at the constrictedlocation to hold the blood vessel open. The stent is typically placedover a deflated medical dilation balloon and positioned in theconstriction. The balloon is then inflated one or more times to expandthe stent in the blood vessel. After the stent has been positioned andexpanded, the balloon is deflated and removed, leaving the expandedstent in the blood vessel. Often, high dilation pressures, for example10-20 atmospheres are required to expand a stent. One concern in stentplacement and dilation is the possibility of the balloon being puncturedat the ends of the stent where the strain on the balloon is thegreatest. If the balloon fails, during stent expansion, it may be caughton a partially expanded stent, possibly requiring surgical intervention.

FIG. 4A is a side view of an embodiment of a medical balloon 400 havinga step-wise variable fiber pitch with a higher pitch at selectedlocations along the balloon. As illustrated, balloon 400 includes agenerally cylindrical barrel portion 402 having a working length L4, aproximal end 404 and a distal end 406. Barrel portion 402 is disposedbetween a proximal cone portion 408 and a distal cone portion 410.Proximal and distal neck portions 412, 414 extend longitudinally fromproximal and distal cone portions 408 and 410. In the illustratedembodiment, one or more fibers 430 extend circumferentially around thediameter of balloon 400 from the proximal end 432 to the distal end 434of balloon 400.

FIG. 4B is graph illustrating the change in fiber pitch over the workinglength of balloon 400. As illustrated, barrel portion 402 includes aproximal zone 416 and a distal zone 418 having a higher fiber pitch thanthe remainder of the barrel portion. For example, zones 416 and 418 mayhave a fiber pitch of 60 wraps per inch of fiber 430 while the remainderof the balloon may have a fiber pitch of 30 wraps per inch. Zones 416and 418 are separated by a central zone 417 having a lower fiber pitchwith zones 416 and 418 spaced apart such that the ends 422 of a stent420 having a length LS are positioned over highly reinforced zones 416and 418 of barrel portion 402 of balloon 400. The increased fiber pitchin zones 416 and 418 serves to increase the strength and punctureresistance of balloon 400 at the ends of stent 420 during deployment andexpansion of the stent.

Although as illustrated, zones 416, 418 are shown near or adjacent tothe proximal and distal ends 404, 406 of barrel portion 402, the zonesmay be positioned in other locations along barrel portion 402 so long asthe ends of a stent placed over the balloon are positioned over thehighly reinforced zones. For example, it may be desirable to have distalzone 418 positioned further away from distal end 406 of barrel portion402 to increase the flexibility and trackability of the distal portionof balloon 400. In the illustrated embodiment, the fiber pitch inproximal and distal cone and neck portions 408-414 is the same orsubstantially the same as the fiber pitch in the adjacent portions ofbarrel portion 402 (e.g. lower than that of reinforced zones 416, 418).In other embodiments, the fiber pitch in proximal and distal cone andneck portions 408-414 may be varied to improve characteristics ofballoon 400 such as the trackability of the balloon.

Medical dilation balloons may be used to break hard, calcified lesionsin blood vessels. Such procedures may involve high dilation pressuresand the concurrent risk that a sharp surface of the lesion may punctureor rupture the dilation balloon. FIG. 5A is a side view of an embodimentof a medical balloon 500 having a variable fiber pitch including ahighly reinforced section. As illustrated, balloon 500 includes agenerally cylindrical barrel portion 502 with a working length L5, aproximal end 504 and a distal end 506. Barrel portion 502 is disposedbetween a proximal cone portion 508 and a distal cone portion 510.Proximal and distal neck portions 512, 514 extend longitudinally fromproximal and distal cone portions 508 and 510. In the illustratedembodiment, one or more fibers 530 extend circumferentially around thediameter of balloon 500 from the proximal end 532 to the distal end 534of balloon 500.

FIG. 5B is a graph illustrating the change in fiber pitch over theworking length of balloon 500. As illustrated, barrel portion 502includes a proximal zone 515, a central zone 516 and a distal zone 517.As illustrated, zone 516 has a higher fiber pitch than the remainder ofthe barrel portion. For example, zone 516 may have a fiber pitch of 60wraps of fiber 530 while proximal zone 515 and distal zone 517 may havea fiber pitch of 30 wraps per inch. Other fiber pitches are possibledepending upon factors such as fiber size, the material from which fiberor fibers 530 are fabricated and desired wall thickness. The increasedfiber pitch in zone 516 serves to increase the strength and punctureresistance of balloon 500 in the zone. The fiber pitch in cone portions508, 510 and neck portions 512, 514 may be the same as or different fromthe fiber pitch in the adjacent proximal and distal barrel zones 515 and517, respectively. In one embodiment, zone 516 may include a radioopaque marker 518 such as a radio-opaque coating. Radio-opaque marker518 enables a practitioner using balloon 500 to position the balloon atthe desired location in the blood vessel when performing angioplasty.

In some instances, a practitioner may use a dilation balloon to launchand/or deploy multiple stents at the same time. For example, if theavailable stents are not as long as the stenosis to be expanded, thepractitioner may position two stents on a single dilation balloon with,for example, the proximal end of the distal stent overlapping the distalend of the proximal stent. However, overlapping stents in this fashiontends to create stress on the dilation balloon in the overlapped areawhen the balloon is inflated to expand the stents.

Referring now to FIG. 6A, in one embodiment, a medical dilation balloon600 having variable pitch reinforcing fibers adapted to launch multiplestents having overlapping ends includes multiple highly reinforcedareas. In one embodiment, balloon 600 includes a generally cylindricalbarrel portion 602 with a working length L6, a proximal end 604 and adistal end 606. Barrel portion 602 is disposed between a proximal coneportion 608 and a distal cone portion 610. Proximal and distal neckportions 612, 614 extend longitudinally from proximal and distal coneportions 608 and 610. In the illustrated embodiment, one or more fibers630 extend circumferentially around the diameter of balloon 600 from theproximal end 632 to the distal end 634 of balloon 600.

FIG. 6B is graph illustrating the change in fiber pitch over the workinglength of balloon 600. As illustrated, barrel portion 602 includeslongitudinally spaced apart proximal, intermediate and distal zones 616,618 and 620 having a higher fiber pitch than the remainder of the barrelportion. In one variation, zones 616, 618 and 620 are separated bylongitudinally spaced apart zones 617 and 619 which have a lower fiberpitch. For example, zones 616, 618 and 620 may have a fiber pitch of 60wraps of fiber 630 while the remainder of the balloon, including zones617 and 619, may have a fiber pitch of 30 wraps per inch. In othervariations, the fiber pitch in intermediate zone 618 may be greater thanthe fiber pitch in proximal and distal zones 616, 620 which in turn, maybe higher than in other portions of balloon 600. Other fiber pitches inthe different zones are possible. As illustrated, zones 616 and 620 arespaced apart such that a proximal end of proximal stent 622 may beplaced over zone 616 and the distal end of a distal stent 624 may beplaced over zone 620. The overlapping end portions 626 of stents 622 and624 are positioned over intermediate zone 618. The increased fiber pitchin zones 616 and 620 serves to increase the strength and punctureresistance of balloon 600 at the proximal end of proximal stent 622 andat the distal end of distal stent 624. The increased fiber pitch inintermediate zone 618 increases the strength and puncture resistance inthe area of the overlapping stent ends.

As illustrated, proximal and distal zones 616, 620 are shown near oradjacent to the proximal and distal ends 604 and 606 of barrel portion602 with intermediate zone 618 centrally located between the proximaland distal zones. In other variations, zones 616, 618 and 620 may bepositioned in other locations along the barrel portion so long as theends and overlapping portions of stents 622 and 624 are positioned overthe highly reinforced zones. For example, if stents 622 and 624 havedifferent lengths, intermediate zone 618 may be closer to the proximalend 604 or distal end 606 of barrel portion 602. It may also bedesirable to have distal zone 620 positioned further away from distalend 606 of barrel portion 602 to increase the flexibility andtrackability of the distal portion of balloon 600. In one embodiment,the fiber pitch in proximal and distal cone and neck portions 608-614 isthe same or substantially the same as the fiber pitch in the adjacentportions of barrel portion 602 (e.g. lower than that of reinforced zones616, 618 and 620). In other embodiments, the fiber pitch in proximal anddistal cone and neck portions 608-614 may be varied to improvecharacteristics of balloon 600 such as the strength and trackability ofthe balloon.

Turning now to FIG. 7, in one embodiment, a method of fabricating aballoon having variable pitch reinforcing fibers begins with theformation of a base balloon 700. Base balloon 700 corresponds to polymerlayer 128 of FIG. 1C and may be formed with conventional blow moldingtechniques or by coating a removable mandrel having the desired finalshape of the balloon with one or more layers of a polymer solution,curing the solution and removing the mandrel. In other variations, baseballoon 700 may be formed from other materials such as a polyethylene,nylon or a polyether block amide (PEBA). A hollow tube-shaped mandrel702 having a side opening 704 is inserted through the balloon and theneck portions 706, 708 of base balloon 700 are sealed against themandrel. A source of pressurized air 716 is connected to mandrel 702 andbase balloon 700 is pressurized through opening 704.

Referring still to FIG. 7, with base balloon 700 pressurized, one ormore flattened reinforcing hoop fibers 710 are wound circumferentiallyaround the base balloon. In one embodiment, a single reinforcing hoopfiber 710 is wound circumferentially from the proximal end of proximalneck portion 706 to the distal end of distal neck portion 708. Flattenedfibers 710 may be supplied from a storage drum or spool 712. Thecircumferential winding of fiber 710 may be accomplished by revolvingspool 712 around mandrel 702 and balloon 700 while indexing the mandreland balloon past the spool. In other embodiments, mandrel 702 andballoon 700 may be rotated as spool 712 is indexed along the length ofbase balloon 700. In any case, the pitch at which fiber 710 is appliedto base balloon 700 may be controlled by varying the linear speed atwhich mandrel 702 and balloon 700 are indexed past spool 712 or viceversa. Alternatively, the pitch may be varied by controlling the rate atwhich fiber 710 is wound onto the balloon while indexing the mandrel 702and balloon 700 (or spool 712) at a constant linear speed. In eithercase, the fiber of the fiber layer extends around the longitudinal axisof the balloon in a series of circumferential fiber wraps over thelength of the barrel wall with the distance between adjacent fiber wrapsvarying according to linear speed at which mandrel 702 and balloon 700are indexed past spool 712 or vice versa. The distance between the fiberwraps may be varied in a step-wise fashion or in a linear increasing ordecreasing manner.

Prior to winding the hoop reinforcing fibers 710 onto base balloon 700,an adhesive coating 714 may be applied to the surface of balloon 700 toaid in retaining the fibers at the desired location. The coating 714 maybe applied by spraying, brushing or dipping and may be selectivelyapplied to different portions of balloon 700. For example, the adhesivemay be applied only to the cone portions of balloon 700 since thetendency for hoop fibers 710 to slip is greatest on the angled surfacesof the cones. Alternatively, an adhesive may be applied to fiber orfibers 710 before the fibers are wound onto the base balloon.

After fibers 710 have been wound onto base balloon 700, an adhesive,such as a polyurethane, may be applied to the outer surface of thefiber-wrapped balloon to facilitate attachment of an outer layer to theballoon. In one embodiment, a thermally-weldable polymer solution suchas a soluble nylon coating may be applied to facilitate thermal bondingin a later processing step. The adhesive and/or polymer solution may beapplied by spraying, brushing or dipping and may be selectively appliedto different portions of balloon 700.

Referring now to FIG. 8, in one embodiment, an outer layer 802 is formedover fibers 710. In one embodiment, outer layer 802 may be a polymertape or film 804 wrapped circumferentially around the balloon 700 at apredetermined pitch 806. Pitch 806 may be selected to be smaller thanthe width of polymer tape 804 so that successive winds of the tape willoverlap, insuring complete coverage of base balloon 700. Tape 804 may besupplied from a storage drum 808. The circumferential winding of tape804 onto balloon 700 may be accomplished by revolving drum 808 aroundmandrel 702 and balloon 700 while indexing the mandrel and balloon pastthe drum. In other embodiments, mandrel 702 and balloon 700 may berotated while drum 808 is indexed along the length of balloon 700.

In one embodiment, tape 804 is wound continuously around balloon 700from the proximal end of proximal neck portion 706 to the distal end ofdistal neck portion 708 of balloon 700 to form a continuous outer layer802 over the entire balloon. Tape 804 may be formed from the samematerial as base balloon 700 or a different material. In one variation,outer layer 802 may be formed from a PEBA, (e.g., Pebax®) tape or film,stretched to a thickness of about 0.0003 inches. In one variation, theside of tape 804 to be applied to base balloon 700 may be coated with anadhesive 810, such as a polyurethane, to facilitate placement of thetape on base balloon 700. Adhesive 810 may be applied to tape 804 byspraying, brushing, dipping or other means.

Turning to FIG. 9, after outer coating 802 has been applied to baseballoon 700 over fibers 710, the balloon, still mounted on mandrel 702is placed into a die 900 having a balloon-shaped cavity 902 and heated.Balloon 700 may be pressurized through mandrel 702 to conform the wallsof the balloon to the inner walls 904 of the die during the heatingprocess. In one embodiment, die 900 may be placed in an oven during theheating process. In another variation, die 900 may include internalheating elements.

During the heating process, base balloon 700 and/or outer coating 802may soften sufficiently to encapsulate fibers 710 in a continuouspolymer matrix as illustrated in FIG. 1C. If base balloon 700 and outercoating 802 are thermally-weldable materials, the two layers may fusetogether during the process. In some embodiments, outer layer 802 mayplastically deform under heat and pressure to even out any surfaceirregularities, for example locations where tape 804 has been overlappedsuch that the outer surface of the finished balloon is continuous andsmooth.

It will be appreciated by those skilled in the art having the benefit ofthis disclosure that a medical balloon with variable pitch reinforcingfibers balloon may provide improved flexibility and trackability withincreased strength and puncture resistance in selected areas of theballoon. It should be understood that the drawings and detaileddescription herein are to be regarded in an illustrative rather than arestrictive manner, and are not intended to be limiting to theparticular forms and examples disclosed. On the contrary, included areany further modifications, changes, rearrangements, substitutions,alternatives, design choices, and embodiments apparent to those ofordinary skill in the art, without departing from the spirit and scopehereof, as defined by the following claims. Thus, it is intended thatthe following claims be interpreted to embrace all such furthermodifications, changes, rearrangements, substitutions, alternatives,design choices, and embodiments.

1-20. (canceled)
 21. A fiber-reinforced medical balloon that may beinflated and deflated, the balloon comprising: a fiber layer embedded ina continuous matrix of polymer material defining a generally cylindricalbarrel wall; wherein the fiber of the fiber layer extendscircumferentially around a longitudinal axis of the balloon over atleast a portion of said barrel wall; and wherein the fiber pitch in afirst portion of the barrel wall is less than the fiber pitch in asecond portion of the barrel wall.
 22. The fiber-reinforced medicalballoon of claim 21 wherein the fiber pitch decreases from a proximalportion of the barrel wall to a distal portion of the barrel wall. 23.The fiber-reinforced medical balloon of claim 21 wherein the fiber pitchdecreases from a proximal portion of the barrel wall to a distal portionof the barrel wall in step-wise increments.
 24. The fiber-reinforcedmedical balloon of claim 21 wherein the fiber pitch in first and secondlongitudinally spaced apart portions of the barrel wall is greater thanthe fiber pitch in a third portion of the barrel wall separating thespaced apart portions.
 25. The fiber-reinforced medical balloon of claim21 wherein the fiber pitch in first and second longitudinally spacedapart portions of the barrel wall is less than the fiber pitch in athird portion of the barrel wall separating the first and secondportions.
 26. The fiber-reinforced medical balloon of claim 21 whereinthe fiber pitch in first, second and third longitudinally spaced apartportions of the barrel wall is greater than the fiber pitch inlongitudinally spaced apart fourth and fifth portions of the barrel wallseparating the first, second and third longitudinally spaced apartportions of the barrel wall.
 27. The fiber-reinforced medical balloon ofclaim 21 wherein the balloon is semi-compliant.
 28. The fiber-reinforcedmedical balloon of claim 21 wherein the balloon is non-compliant. 29.The fiber-reinforced medical balloon of claim 21 wherein the fibers aresubstantially ribbon-shaped.
 30. The fiber-reinforced medical balloon ofclaim 29 wherein the fibers have a width-to-thickness ratio in the rangefrom about 25:1 to about 45:1.
 31. The fiber-reinforced medical balloonof claim 29 wherein the fibers have a width-to-thickness ratio in therange from about 30:1 to about 40:1.
 32. A medical balloon that may beinflated and deflated, the balloon comprising: a fiber layer comprisedof ribbon-shaped fiber embedded in a continuous matrix of polymermaterial defining a generally cylindrical barrel wall; wherein the fiberof the fiber layer extends around a longitudinal axis of the balloon ina series of circumferential fiber wraps over at least a portion of thebarrel wall, wherein the distance between the fiber wraps defines afiber pitch; and wherein the distance between adjacent fiber wrapsvaries over the barrel wall in non-linear increments.
 33. The medicalballoon of claim 32 wherein the distance between adjacent fiber wrapsvaries in step-wise increments.
 34. The medical balloon of claim 32wherein the fibers have a width-to-thickness ratio in the range fromabout 25:1 to about 45:1.
 35. The medical balloon of claim 32 whereinthe fibers have a width-to-thickness ratio in the range from about 30:1to about 40:1.
 36. The medical balloon of claim 32 wherein the fiberpitch in first and second longitudinally spaced apart portions of thebarrel wall is greater than the fiber pitch in a third portion of thebarrel wall separating the spaced apart portions.
 37. The medicalballoon of claim 32 wherein the fiber pitch in first and secondlongitudinally spaced apart portions of the barrel wall is less than thefiber pitch in a third portion of the barrel wall separating the firstand second portions.
 38. The medical balloon of claim 32 wherein thefiber pitch in first, second and third longitudinally spaced apartportions of the barrel wall is greater than the fiber pitch inlongitudinally spaced apart fourth and fifth portions of the barrel wallseparating the first, second and third longitudinally spaced apartportions of the barrel wall.
 39. The medical balloon of claim 32,wherein the barrel wall includes proximal and distal ends disposedbetween tapered cone walls and proximal and distal cylindrical neckwalls extending therefrom along the longitudinal axis of the balloon,and wherein the fiber layer extends continuously between the ends of theneck walls around the cone sections and barrel wall.
 40. Afiber-reinforced medical balloon that may be inflated and deflated, theballoon comprising: a base balloon formed from a polymer materialdefining a generally cylindrical barrel wall; a fiber layer extendingaround a longitudinal axis of the balloon in a series of circumferentialfiber wraps over the length of the barrel wall wherein the distancebetween the fiber wraps defines a fiber pitch; an outer layer formedover the fiber layer, the outer layer comprising a polymer material indirect contact with the base balloon; and wherein the fiber pitch in afirst portion of the barrel wall is less than the fiber pitch in asecond portion of the barrel wall.